Centerless grinder with hydraulic drive

ABSTRACT

A centerless grinder having a grinding wheel and coacting regulating wheel with a separate hydrostatic transmission for driving each of said wheels with each of said transmissions having a hydraulic pump and a hydraulic motor and with the pumps of both hydrostatic transmissions connected to output shaft means of a main drive motor whereby both of said wheels are driven and when the regulating wheel functions as a brake the energy imparted thereto through the drive of the grinding wheel is fed back to the main drive motor to assist in driving the grinding wheel. Additionally feed rolls provided for advancing a workpiece to and from the grinding wheel are driven by the hydrostatic transmission for the regulating wheel with the motors thereof in series with the motor for the regulating wheel to operate in the same manner as the motor for the regulating wheel and with the pump and motors of the second hydrostatic transmission being of the variable displacement type.

United States Patent [191 Schaller Dec. 9, 1975 CENTERLESS GRINDER WITH HYDRAULIC DRIVE Robert L. Schaller, Camilius, NY.

[73] Assignee: Sundstrand Syracuse, Inc.,

Syracuse, NY.

[22] Filed: Feb. 16, 1973 [21] Appl. No.: 332,811

[44] Published under the Trial Voluntary Protest Program on January 28, 1975 as document no.

[75] Inventor:

[52] US. Cl. 51/103 TF; 51/1345 R [51] Int. Cl. B24B 5/22 [58] Field of Search 51/134.5, DIG. 16, 103 R, 51/103 TF; 60/483, 486

[56] References Cited UNITED STATES PATENTS 2,073,079 3/1937 Theler et a] 51/103 TF 3,534,507 10/1970 Barhorst 51/103 R [57] ABSTRACT A centerless grinder having a grinding wheel and coacting regulating wheel with a separate hydrostatic transmission for driving each of said wheels with each of said transmissions having a hydraulic pump and a hydraulic motor and with the pumps of both hydrostatic transmissions connected to output shaft means of a main drive motor whereby both of said wheels are driven and when the regulating wheel functions as a brake the energy imparted thereto through the drive of the grinding wheel is fed back to the main drive motor to assist in driving the grinding wheel. Additionally feed rolls provided for advancing a workpiece to and from the grinding wheel are driven by the hydrostatic transmission for the regulating wheel with the motors thereof in series with the motor for the regulating wheel to operate in the same manner as the motor for the regulating wheel and with the pump and motors of the second hydrostatic transmission being of the variable displacement type.

7 Claims, 1 Drawing Figure U.S. Patent Dec. 9 1975 w \m mx NW Q NN g m ME I ,1 i. I n \w an JR J E M n. ww Kw CENTERLESS GRINDER WITH HYDRAULIC DRIVE BACKGROUND OF THE INVENTION This invention pertains to centerless grinders wherein a workpiece is supported on a work rest and is engaged by a grinding wheel with a regulating wheel backing up the workpiece and with provision in the drive for the components of the centerless grinder to have energy transmitted to the regulating wheel during grinding of a workpiece fed back through a hydrostatic transmission to add to the power imparted to the grinding wheel.

The centerless grinder is generally of the type disclosed in Schaller US. Pat. No. 3,503,156 wherein power-driven feed rolls are positioned at both sides of a grinding station and with the grinding station having a grinding element as well as a work rest support for the workpiece and a regulating wheel, as shown in FIG. 11 of said Patent. In the Patent, the grinding element is shown as an endless belt; however, in the embodiment disclosed in this application, the grinding element is shown as a grinding wheel. The disclosure of the Schaller Patent as to the general construction of a centerless grinder is incorporated herein by reference.

At the present time, most regulating wheel drives on centerless grinders have a low magnitude horsepower. In the future, higher horsepower requirements for the grinding element and high wheel speeds will raise the horsepower of the regulating wheel substantially. In part, this will be due to the fact that much higher through feed rates of the order of ten times that being experienced today will be achieved. During grinding, the regulating wheel functions as a brake and receives energy imparted thereto by the grinding wheel and rotation of the workpiece. At the present time, this energy is dissipated in the form of heat and in other ways through the worm wheel drives of the regulating wheel motor. In actual fact, the regulating wheel motor turns into a pump to provide the braking action of the regulating wheel. This has resulted in a waste of energy in the system. C

SUMMARY A principal advantage of the invention disclosed herein is to provide a drive system for a centerless grinder whereby energy imparted to the regulating wheel when the regulating wheel functions as a brake is returned through the system to assist in driving the grinding element, such as a grinding wheel. More particularly, the grinding element and the regulating wheel are driven by hydraulic systems with a main power source having output shaft means connected to hydraulic pumps, one for each of the grinding element and the regulating wheel, and with each pump being connected to a motor whereby operation of the pumps causes operation of the motors to rotate the grinding element and the regulating wheel and when the regulating wheel functions as a brake the function of the pump and motor therefor are reversed to have the pump connected to the prime mover function as a motor and thereby assist the prime mover in driving the pump for the system driving the grinding wheel.

An object of this invention is to provide a centerless grinder having a grinding wheel and a coacting regulating wheel, a first hydrostatic transmission for driving the grinding wheel, a second hydrostatic transmission for driving the regulating wheel, each of said transmis- 2 sions including a pump and a motor, and a main motor having output shaft means connected to the pumps of both of said hydrostatic transmissions whereby the regulating wheel functions to assist said main motor when the regulating wheel is functioning as a brake.

Still another object of the invention is to provide a centerless grinder as defined in the preceding paragraph wherein there are feed rolls positioned at both sides of the grinding wheel with said second hydrostatic transmission including motors for said feed rolls in series with the first mentioned motor of said second hydrostatic transmission.

An additional object of the invention is to provide a centerless grinder as defined in the preceding paragraphs wherein said pump and motors of said second hydrostatic transmission are of the variable displacement type to permit adjustment in the speed of rotation of the regulating wheel and feed rolls to compensate for wear thereof.

BRIEF DESCRIPTION OF THE DRAWING The FIGURE is a fragmentary plan view of the centerless grinder with certain parts shown diagrammatic'ally.

DESCRIPTION OF THE PREFERRED EMBODIMENT The centerless grinder has a grinding element which is shown as a rotatable grinding wheel 10 mounted on a shaft 11 rotatable in frame-supported bearings 15 and 16. Coacting with the grinding wheel is a regulating wheel 20 rotatably mounted in frame-supported bearings 21 and 22 by a shaft 23. An additional element is a work rest blade (not shown) which is positioned between the grinding wheel 10 and the regulating wheel 20 to support a workpiece in the form of bar stock 25.

As shown more particularly in Schaller US. Pat. No. 3,503,156, the disclosure of which is incorporated herein by reference, there are a plurality of pairs'of feed rolls positioned at either side of the grinding wheel 10 and'regulating wheel 20. Representative of these is a pair of feed rolls 30 and 31 positioned at one side of the wheels and a second pair of feed rolls 32 and 33 positioned at the other side. As conventional in centerless grinders, the feed rolls and the regulating wheel are set at a helix. angle providing an angle of inclination whereby rotation of the regulating wheel 20 and the feed rolls imparts longitudinal advance to the bar stock 25. v

The drive of the grinding wheel 10 is by means of a hydrostatic transmission driven by a prime mover in the form of a double-ended electric motor 40 having coupled output shafts 41 and 42. A suitable hydrostatic transmission for use in driving the grinding wheel 10 as well as regulating wheel 20 is that of the type offered by Sundstrand Corporation. An example of a hydrostatic transmission of the general type that could be used is shown in US. Pat. No. 3,212,263 and the disclosure thereof is incorporated herein by reference. The hydrostatic transmission for the grinding wheel 10 includes a pump 45 which is of the variable volume or displacement type and typically has a swash plate which is adjustable to control the volume output thereof. Pump 45 is connected to a hydraulic motor 46 by a pair of fluid lines 47 and 48. As conventionally known in a hydrostatic transmission, there is some additional circuitry including a charge line for replenishing fluid in the, system; however, this known structure is not disclosed 3 herein. The hydraulic motor 46 is connected to the shaft 11 of the grinding wheel by a coupling 49.

The output shaft 42 which, with the shaft 41, provides output shaft means for the electric motor 40 is connected to a pump 50 of a second hydrostatic transmission and which is of the same type as the pump 45 of the first hydrostatic transmission. This pump is connected by a line 51 to a hydraulic motor 52 of the second hydrostatic transmission, with the latter being connected to the shaft 23 of the regulating wheel.

The second hydrostatic transmission system includes hydraulic motors 53 and 54 which are connected to the feed rolls for driving at least one feed roll of each pair with a suitable interconnecting mechanical drive for driving the other feed roll of the pair, as indicated diagrammatically at 55 and 56. The drives may include universal joints 58 as indicated diagrammatically.

The hydraulic motors 52, 53 and 54 of the second hydrostatic transmission are connected in series with flow from motor 52 passing through line 60 to the motor 54 and with flow therefrom passing through line 61 to the hydraulic motor 53 and with return flow from motor 53 to the pump 50 being through a line 62. The motors 52, 53 and 54 are of the variable displacement type wherein the speed at which they drive the component associated therewith may be varied in order to compensate for wear of the particular component.

In operation, the elelctric motor 40 drives the pumps of the two hydrostatic transmissions whereby the grinding wheel is rotated at a desired speed and the regulating wheel as well as the feed rolls are driven to advance a workpiece into grinding relation with the grinding wheel. At this time, the regulating wheel 20 and the feed rolls function as a brake to retard rotation of the workpiece and energy imparted thereto from the grinding wheel results in reversal of the operation of pump 50 and motors 52, 53 and 54 to have the pump 50 function as a motor and the motors 52-54 function as pumps. This causes the pump 50, now functioning as a motor, to assist the electric motor 40 in driving the pump 45 of the first hydrostatic transmission which is rotating the grinding wheel.

With both of the pumps 45 and 50 being of the variable volume type, the set control speeds of the grinding wheel 10 and the regulating wheel 20 as well as the feed rolls can be set by adjusting the pumps, as by varying the displacement of the wobble plate thereof.

I claim:

1. In a centerless grinder, a grinding wheel and a coacting regulating wheel, a first hydrostatic transmission for driving said grinding wheel, a second hydrostatic transmission for driving the regulating wheel, each of said transmissions including a pump and a motor, and a main motor having output shaft means connected to the pumps of both of said hydrostatic transmissions whereby the regulating wheel functions to assist said main motor when the regulating wheel is functioning as a brake.

2. A centerless grinder as defined in claim 1 and having feed rolls positioned at both sides of the grinding wheel, and said second hydrostatic transmission including motors for said feed rolls in series with the first mentioned motor of said transmission.

3. A centerless grinder as defined in claim 2 wherein said pumps are of the variable displacement type and the motors of said second hydrostatic transmission are of the variable displacement type to permit adjustment for wear of the parts driven thereby.

4. In a centerless grinder, a grinding wheel and a coacting regulating wheel, a prime mover for supplying power to operate said wheels and having a pair of output shafts, a first hydraulic drive for driving said grinding wheel including a hydraulic pump connected to one of said output shafts and a hydraulic motor in circuit with the pump and connected to the grinding wheel, a second hydraulic drive including a second hydraulic pump connected to the second of the output shafts and a second hydraulic motor connected to the regulating wheel and the second pump whereby said prime mover drives both said regulating wheel and the grinding wheel and energy imparted to the regulating wheel by the grinding wheel is delivered through said second hydraulic drive to assist the prime mover in driving the grinding wheel.

5. In a centerless grinder as defined in claim 4, a plurality of feed rolls for feeding a workpiece to and away from the grinding wheel, and said second hydraulic drive including additional hydraulic motors for said feed rolls which are in circuit with said second hydraulic pump.

6. In a centerless grinder, a travelling grinding element and a coacting regulating wheel, feed rolls positioned at both sides of said element and wheel to feed a workpiece relative thereto and assist the regulating wheel in holding rotation of a workpiece to a desired rate during grinding, an electric motor, a first hydrostatic transmission for driving said grinding element including a pump connected to an output shaft of said electric motor and a fluid motor operatively connected to the grinding element, a second hydrostatic transmis sion including a pump connected to the output shaft of the electric motor and a series of fluid motors in series and connected to the regulating wheel and the feed rolls, whereby power is delivered from the electric motor to the regulating wheel and feed rolls to advance a workpiece and power is returned to the electric motor when the regulating wheel and feed rolls are braking a workpiece engaged by the grinding element.

7. A centerless grinder as defined in claim 6 wherein the pump and motors of the second hydrostatic transmission are of the variable displacement type. 

1. In a centerless grinder, a grinding wheel and a coacting regulating wheel, a first hydrostatic transmission for driving said grinding wheel, a second hydrostatic transmission for driving the regulating wheel, each of said transmissions including a pump and a motor, and a main motor having output shaft means connected to the pumps of both of said hydrostatic transmissions whereby the regulating wheel functions to assist said main motor when the regulating wheel is functioning as a brake.
 2. A centerless grinder as defined in claim 1 and having feed rolls positioned at both sides of the grinding wheel, and said second hydrostatic transmission including motors for said feed rolls in series with the first mentioned motor of said transmission.
 3. A centerless grinder as defined in claim 2 wherein said pumps are of the variable displacement type and the motors of said second hydrostatic transmission are of the variable displacement type to permit adjustment for wear of the parts driven thereby.
 4. In a centerless grinder, a grinding wheel and a coacting regulating wheel, a prime mover for supplying power to operate said wheels and having a pair of output shafts, a first hydraulic drive for driving said grinding wheel including a hydraulic pump connected to one of said output shafts and a hydraulic motor in circuit with the pump and connected to the grinding wheel, a second hydraulic drive including a second hydraulic pump connected to the second of the output shafts and a second hydraulic motor connected to the regulating wheel and the second pump whereby said prime mover drives both said regulating wheel and the grinding wheel and energy imparted to the regulating wheel by the grinding wheel is delivered through said second hydraulic drive to assist the prime mover in driving the grinding wheel.
 5. In a centerless grinder as defined in claim 4, a plurality of feed rolls for feeding a workpiece to and away from the grinding wheel, and said second hydraulic drive including additional hydraulic motors for said feed rolls which are in circuit with said second hydraulic pump.
 6. In a centerless grinder, a travelling grinding element and a coacting regulating wheel, feed rolls positioned at both sides of said element and wheel to feed a workpiece relative thereto and assist the regulating wheel in holding rotation of a workpiece to a desired rate during grinding, an electric motor, a first hydrostatic transmission for driving said grinding element including a pump connected to an output shaft of said electric motor and a fluid motor operatively connected to the grinding element, a second hydrostatic transmission including a pump connected to the output shaft of the electric motor and a series of fluid motors in series and connected to the regulating wheel and the feed rolls, whereby power is delivered from the electric motor to the regulating wheel and feed rolls to advance a workpiece and power is returned to the electric motor when the regulating wheel and feed rolls are braking a workpiece engaged by the grinding element.
 7. A centerless grinder as defined in claim 6 wherein the pump and motors of the second hydrostatic transmission are of the variable displacement type. 